Quantification Approach

Data Source

Provided by

Water Infrastructure Group; Barossa Infrastructure Limited (BIL); Willunga Basin Water Company (WBWC); South Australian Department for Water.

Method

Virginia Pipeline Scheme

The volume reported is from a meter at the Virginia Pipeline Scheme pump station.

Barossa Infrastructure Limited

The volume of water supplied to the customers was derived by subtracting the volume of leakage (line item 20.3) from the total volume of water delivered to BIL (sum of line items 12.6 and 12.18).

Calculation of volume of water supplied to BIL customers in the 2010–11 year

Calculation

Volume (ML)

12.6 Delivery of water to irrigation scheme under inter-region agreement

2,301

12.18 Other irrigation water increases

185

20.3 Leakage to groundwater

(62)

20.4 Application of water for irrigation

2,424

Willunga Basin Water Company

The volume of water delivered via the Willunga Basin Water Company (WBWC) to customers was provided from WBWC. The volume is roughly equivalent to the inflows to the WBWC reported at line items 12.4 and 12.18.

Assumptions, Limitations, Caveats and Approximations

Virginia Pipeline Scheme

Customers' meters are not read in June or July as this does not correspond to the the irrigation water year. The volume reported was from the Virginia Pipeline Scheme pumping station and therefore the volume actually delivered to customers may be different due to leakage between the pumping station and customer meters.

Estimate that the actual volume of water measured at customers' meters is 5% less due to blocked meters and burst pipes.

Barossa Infrastructure Limited

Customers' meters cannot be used directly as they were read to represent the water year (1 October – 31 September). Instead the water delivered to BIL from all sources, which was collected to represent the financial year, was reduced the volume of leakage. This assumes leakage within the water year represents leakage during the financial year.

The area serviced by BIL extends beyond the boundary of the Adelaide region. It was assumed that the length of BIL infrastructure outside the Adelaide region is insignificant.

Uncertainty Information

The uncertainty estimate was not quantified.

Comparative year

This corresponds to line item 20.3.1 Application of irrigation water from water distribution system reported in the National Water Account 2010. In 2011 there were two important changes to the way in which this item was reported:

In 2010 this line item was reported as part of the water distribution system store (urban water supply system), however in 2011 the Irrigation water supply system has been reclassified as a separate store.

In 2010 only the irrigation scheme operated by BIL was reported on, however in 2011 two additional irrigation schemes were reported on.

Despite these changes, the restated volume for this item was unchanged (4,890 ML). Data on volumes of water delivered to irrigation scheme users from the Virginia Pipeline Scheme and the Willunga Basin Water Company was not available for the 2009–10 year.